This invention relates to an improved toner cartridge for use in a laser printer and, more particularly, to a toner cartridge for use in a laser printer in which more of the toner is effectively utilized with an additional paddle for moving toner not moved by a main or first paddle.
It has previously been suggested in U.S. Pat. No. 5,875,378 to Campbell et al, which is incorporated by reference herein, to use a single paddle to sweep a hopper or toner reservoir in a toner cartridge of a laser printer to agitate the toner therein and produce more effective utilization thereof.
Because of the internal geometry of the toner reservoir or hopper of the toner cartridge in the aforesaid Campbell et al patent, the single paddle of the aforesaid Campbell et al patent is incapable of reaching all volumes of the toner reservoir or hopper. This is because a portion of the hopper or toner reservoir has a non-circular portion, which results in a smaller cross section of the hopper or toner reservoir, in its bottom adjacent one of its end walls.
As a result, a significant amount of toner is not used at the end of the life of a toner cartridge. Some of this unused toner can be utilized through a user shaking the toner cartridge after removing it from the laser printer and then returning the toner cartridge to the laser printer after shaking.
The toner moving paddle in the aforesaid Campbell et al patent has been constructed so that its outer toner moving bar avoids sweeping the non-circular portion of the hopper or toner reservoir. The non-circular portion constitutes an inset in the inner surface of the toner reservoir or hopper wall to provide increased space exterior of the toner reservoir or hopper for rollers in the laser printer for feeding each sheet of a medium for printing.
Additionally, it has previously been suggested in U.S. Pat. No. 5,634,169 to Barry et al, which is incorporated by reference herein, to use a toner level sensing system in a toner cartridge of the type shown and described in the aforesaid Campbell et al patent. This toner level sensing system senses the level of the toner in the toner cartridge by sensing the torque created by the toner on the moving paddle because the torque on the moving paddle is reduced as the toner level decreases. Thus, any structure producing an additional torque on the toner moving paddle during each revolution of the toner moving paddle would render the toner level sensing system ineffective, particularly at relatively low levels of toner in the toner cartridge.
Furthermore, an improved toner, insofar as reducing the required fuser temperature, has substantially worse powder flow and angle of repose properties than the prior toner. These properties increase the propensity of the improved toner to cling to portions of the hopper or toner reservoir that are not reached by the single paddle of the aforesaid Campbell et al patent. This also affects the ability to deliver toner to a developer roll of the laser printer.
The improved toner is monocomponent, which can become stagnant and cohesive when left undisturbed for a period of time. This stagnation and settling of the toner may be aggravated by the slight vibrations generated by the printer motor and gear train in a laser printer.
The toner cartridge of the present invention utilizes a second paddle in conjunction with the first paddle to sweep most of the volume that the first paddle has been incapable of sweeping. Therefore, more of the toner is swept by the combined paddles of the present invention than by the single paddle in the aforesaid Campbell et al patent so that more toner is available for use.
The present invention has the second paddle pivotally supported on the first paddle, which revolves about a fixed first axis, so that the second paddle pivots about a second axis substantially parallel to the fixed first axis about which the first paddle revolves. Thus, sweeping of almost all of the volume of the toner reservoir is accomplished with the two paddles of the present invention.
The second paddle also engages a portion of the longitudinal wall of the toner reservoir to remove more of the toner therefrom than is accomplished with the first paddle. The first paddle has a slight clearance with respect to all of the walls of the toner reservoir.
The toner level sensing system of the aforesaid Barry et al patent is not affected by the use of the second paddle. This is because the toner level sensing system senses the torque when the first paddle is at substantially its lowermost position and the second paddle trails the first paddle so that it is not creating any significant torque when the torque on the first paddle is sensed by the toner level sensing system.
The use of the second paddle reduces the need for a user to shake the toner cartridge to obtain the use of more toner in the toner cartridge. This is because most of the toner, which could be dislodged by shaking, had already been removed by the second paddle.
This invention relates to a toner cartridge comprising a toner reservoir having toner therein and a first paddle rotatable in the toner reservoir about a fixed first axis. The toner reservoir has a first portion in which the toner therein is engaged by the first paddle to agitate the toner and to push the toner out of the toner reservoir during each revolution of the first paddle. A second paddle is pivotally supported on the first paddle for pivotal movement about a second axis substantially parallel to the fixed first axis in response to each revolution of the first paddle about the fixed first axis. The toner reservoir has a second portion in which the toner therein is not engaged by the first paddle during each revolution of said first paddle about the fixed first axis. The second paddle includes a toner moving element for moving through the second portion of the toner reservoir in response to each revolution of the first paddle through the toner reservoir to engage the toner in the second portion of the toner reservoir to agitate the toner and to push the toner out of the toner reservoir during each revolution of the first paddle.
An object of this invention is to provide a toner cartridge for a laser printer to permit agitation of a larger volume of the toner within the hopper or toner reservoir of the toner cartridge.
Other objects of this invention will be readily perceived from the following description, claims, and drawings.